Genes which code for the RNA polymerase of Bacillus subtilis will be purified from both mutant and wild type cells, amplified by cloning, and then the nucleotide sequence determined for those portions of the gene that result in a phenotypic alteration of the host cell. A correlation between mutational site and phenotypic change will be made to determine which parts of the gene are essential for various functions. Physiological characterization of conditional RNA polymerase mutants will continue and the properties of the mutant polymerase in vitro will be tested on a variety of templates. The selection of promotor sites will be tested using a bacteriophage TSP-1 model system and a comparison will be made of wild type and mutant cells at permissive and restrictive temperatures.